It is common for carpet and upholstery cleaning services to be performed from mobile units. The mobile unit includes a motor vehicle, such as a van, which carries means for heating and pressurizing cleaning fluid and a blower for creating a vacuum. Pressurized cleaning fluid is conveyed by a hose to a wand for spraying fluid onto the surface to be cleaned. Another hose connected to the blower and the wand carries spent cleaning fluid and debris from the surface back into the vehicle.
A complete system of this type is disclosed in U.S. Pat. No. 4,940,082 granted Jul. 10, 1990 to James R. Roden for "Cleaning System". In the system disclosed in this patent the pressurizing means and the blower are driven by a separate internal combustion engine dedicated specifically for that purpose.
There is, of course, another power plant available in the internal combustion engine used to propel the vehicle. And others have proposed to provide systems for driving the cleaning system pressurizing means and the blower from that engine, thus eliminating the cost of the separate engine.
One such drive system is disclosed in U.S. Pat. No. 4,336,627 granted Jun. 29, 1982 to Lionel D. Bascus for "Water Conditioning Systems". That system employs an electric clutch associated with the vehicle engine connected to a separate drive shaft which extends through the driver compartment back to a pump located in the cargo compartment.
Another drive system for transmitting power from the vehicle engine to the cleaning system is disclosed in U.S. Pat. No. 5,165,139 granted Nov. 24, 1992 to Myron P. Oxman for "Mobile Cleaning Unit". Oxman proposes to use a hydraulic power transfer system wherein the vehicle engine drives a hydraulic pump through a power take-off and the pump in turn drives a hydraulic motor connected to the pump and blower.
Internal friction in the hydraulic power takeoff circuit generates considerable heat in the circuit. The Oxman patent proposes to dispose of that heat through an oil cooler positioned in the cooling air stream for the vehicle engine. Preferably, this heat can be utilized to heat the cleaning fluid to be sprayed onto the surface to be cleaned.
Mobile cleaning systems can also be utilized in flood restoration work in which the powerful vacuum system is employed to pump water out of a flooded structure. When so utilized, however, no cleaning fluid is conveyed through the system and is therefore not available to remove heat from the hydraulic power takeoff circuit.